JP2003241029A - Optical module and optical transmitter receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module and an optical transmitter receiver which have a compact package and can increase the mount density on a circuit board. <P>SOLUTION: The optical module 20 has a lens 21 and an electronic circuit 23 including a photodiode 22 and can convert a light signal into an electric signal by the photodiode 22. The optical module 20 is equipped with a stem 29 which supports the photodiode 22, etc., a cap member 30 which is joined with the step 29 and holds the lens 21 opposite the photodiode 22, and a sleeve 35 which can hold a ferrule opposite the lens 21. The cap member 30 has an opening 30a for holding the lens 21, the internal diameter D2 of the opening 30a being smaller than the diameter D1 of the lens 21. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module and an optical transceiver, and more particularly to an optical module capable of receiving or transmitting an optical signal, and an optical transceiver having the optical module.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind of field,
The one disclosed by Japanese Patent Laid-Open No. 7-31430 is known. This publication discloses a light receiving module capable of converting an optical signal input through an optical fiber into an electric signal. The light receiving module described in the publication has a condenser lens, a light receiving element such as a photodiode, an electronic circuit including a preamplifier, and a capacitor, and these components are provided in a cylindrical package (PKG). It is housed in. In this case, the ferrule attached to the optical fiber is connected (inserted) to one end of the package.
Further, lead pins for transmitting and receiving electric signals are extended from the other end of the package. That is, in this optical module, the extending direction of the optical fiber and the extending direction of the lead pin are substantially parallel to each other. Therefore, such an optical module is generally called a coaxial optical module.

In the coaxial type optical module as described above,
As a package, a package for a discrete semiconductor such as a transistor (so-called TO type PKG)
Is used. Such a package includes a stem (substrate), a cap member, and a sleeve. The electronic circuit described above is mounted on the stem and electrically connected to the plurality of lead pins. These lead pins extend outward from the stem. The electronic circuit including the photoelectric conversion element on the stem is sealed by the cap member joined to the stem. Further, the cap member holds the lens so as to face the photoelectric conversion element. And in the cap member,
A sleeve made of resin or the like is joined. The sleeve has a hole for inserting the ferrule described above. When the ferrule is inserted into the hole of the sleeve, the ferrule-side optical fiber and the photoelectric conversion element in the cap member can be optically coupled via the lens.

[0004]

By the way, in recent years,
Optical communication using the above-described optical module is rapidly spreading. With the spread of optical communication, the applicable range of the optical module has come to extend to, for example, communication between back panels of computers, which has been used until now, and communication between telephone exchanges. In such applications, it is necessary to dispose a large number of optical modules or optical transceivers having optical modules on an integrated circuit board. In this case, how to increase the mounting density of the optical modules or to make the optical transceivers equipped with the optical modules compact with the increase in the number of the optical modules and the optical transceivers to be installed is a problem. Becomes

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical module and an optical transceiver that have a compact package and can increase the mounting density on a circuit board. .

[0006]

One aspect of the present invention relates to an optical module having a lens and an electronic circuit including a photoelectric conversion element. This optical module is capable of converting one of an optical signal and an electrical signal to the other by a photoelectric conversion element, and includes a stem, a cap member, and
A package including a sleeve is provided. That is, the electronic circuit including the photoelectric conversion element is supported by the stem. A tubular cap member is joined to the stem, and the cap member holds the lens so as to face the photoelectric conversion element on the stem. A sleeve capable of holding an optical fiber (ferrule) is joined to the cap member so as to face the lens.

Here, with respect to this type of optical module, it is required to increase the mounting density on the circuit board, but the mounting density of this type of optical module mainly depends on the outer diameter of the ferrule. . At present, the outer diameter of the ferrule is reduced to about 1.25 mm, and the stem constituting the package is also reduced in diameter in accordance with the outer diameter of the ferrule. For example, according to such a small diameter ferrule, the outer diameter is 3.8 mm, for example.
The stem of is also being used.

However, the outer diameter of the cap is appropriately maintained with respect to the stem diameter, and the strength of the sleeve itself and the strength of the bonding portion between the sleeve and the cap are maintained,
Even if the thickness of the sleeve is made as thin as possible, it is not easy to reduce the outer diameter of the sleeve that determines the maximum outer diameter of the package. For example, if the outer diameter of the stem is 3.
Even if the diameter is reduced to about 8 mm, it is difficult to reduce the outer diameter of the sleeve to 4.5 mm or less. In this way, conventionally, due to the difficulty of reducing the diameter of the sleeve,
It has been hindered to arrange the optical modules in higher density on the circuit board.

In this case, it is substantially difficult to further reduce the outer diameter of the stem. That is, an electronic circuit including a photoelectric conversion element and the like must be mounted on the stem. In addition to this, it is necessary to dispose a plurality of lead pins on the stem for exchanging electric signals with an electronic circuit. For example, 3 for the optical module for transmission,
There are five optical modules for reception (GND, VPD,
VCC, O∪T, / OUT) lead pins are required. On the other hand, in order to reduce the diameter of the stem, it is conceivable to dispose a preamplifier, a capacitor or the like forming an electronic circuit outside the package. However, this is not practical because the signal from the photoelectric conversion element becomes weak and it becomes difficult to secure noise resistance. Therefore, in order to satisfy these conditions, it is necessary to make the package further compact while maintaining at least the outer diameter of the stem at the present minimum value of about 3.8 mm.

Based on such a background, the inventors of the present invention have conducted intensive studies to increase the mounting density of the optical module, and as a result, have paid attention to the fixing position of the spherical lens and the cap member. That is, the cap member is provided with an opening for fixing the spherical lens. However, in the conventional optical module, the inner diameter of the opening is set to be approximately the same as the diameter of the spherical lens (slightly larger). It was being done. In this case, it is necessary to secure a certain amount of space around the opening in order to arrange pellets or the like used for fixing the lens. For this reason, conventionally, it has been difficult to reduce the diameter of the cap member unless the diameter of the lens needs to be reduced, which requires a review of the entire optical system. As a result, the diameter of the sleeve joined to the cap member is reduced. Was difficult. Further, if the diameter of the lens is reduced, the focal length becomes shorter and the height of the cap member becomes shorter. For this reason, the joint area between the cap member and the sleeve becomes small, and it becomes difficult to secure sufficient joint strength.

In consideration of these points, in the optical module of the present invention, the opening for holding the spherical lens of the cap member is formed to have an inner diameter smaller than the diameter of the lens. As described above, if the inner diameter of the opening is smaller than the diameter of the lens, even if a space for fixing the lens is secured around the opening, the outer diameter of the portion of the cap member located on the opening side does not hinder the fixing of the lens. It is possible to set it as small as possible within the range that does not exist. Then, if the outer diameter of the opening side of the cap member is reduced in this way, the wall thickness of the sleeve at the bonding location is secured to some extent in order to secure the strength of the sleeve itself and the bonding strength between the cap member and the sleeve. Even so, it is possible to reduce the maximum outer diameter of the sleeve to at least about the same as the outer diameter of the stem, or even smaller.

Therefore, according to the present invention, the package of the optical module can be made compact, and the packaging density of the optical module on the circuit board can be easily increased.
In this case, the lens held by the cap member is arranged offset to the sleeve side or the stem side. Therefore, if the total height of the cap member is appropriately determined, it is not necessary to review the entire optical system. Further, by adopting such a configuration, the lens can be easily and accurately positioned with respect to the opening, so that the lens mounting accuracy in the optical module can be improved.

In this case, the cap member is on the stem side,
While including a large diameter portion having a first outer diameter, on the opening side, the first
It is preferable to include a small diameter portion having a second outer diameter smaller than the outer diameter of That is, the cross-sectional area of the small diameter portion is smaller than the cross-sectional area of the large diameter portion. As a result, it is possible to secure a necessary and sufficient storage capacity for the electronic circuit including the photoelectric conversion element in the large diameter portion.

Further, it is preferable that the lens is fixed to the opening so as to be located between the cap member and the sleeve.
By adopting such a configuration, if the total height of the cap member is smaller than that of the conventional one, the same optical system as the conventional one can be basically used and the lens can be easily fixed to the cap member. You can

Further, the lens may be fixed to the opening so as to be located between the cap member and the stem. That is, under such a configuration, most of the lens is housed inside the cap member, so that the overall height of the cap member becomes large. As a result, the contact area between the cap member and the sleeve also increases, so that the joint strength between the two can be improved.

By adopting these structures, the maximum outer diameter of the sleeve can be made 4 mm or less. As a result, according to the present invention, the mounting density of the optical module on the circuit board can be further increased.

Further, the photoelectric conversion element is preferably a light receiving element for converting an optical signal input via the optical fiber into an electric signal. In this case, it is preferable that the electronic circuit further includes a preamplifier that amplifies an electric signal from the light receiving element and a capacitor that smoothes a power supply signal to the light receiving element and the preamplifier.

Further, the photoelectric conversion element may be a light emitting element which converts an electric signal input to an electronic circuit into an optical signal.

Another aspect of the present invention relates to an optical transmitter / receiver having a receiving optical module and a transmitting optical module, and transmitting and receiving an optical signal using the receiving optical module and the transmitting optical module. . The receiving optical module of this optical transceiver has a condenser lens and an electronic circuit including a light receiving element, and the light receiving element can convert an optical signal into an electrical signal. This optical module includes a package including a stem, a cap member, and a sleeve. That is, the electronic circuit including the light receiving element is supported by the stem. A cylindrical cap member is joined to the stem, and the cap member holds the condenser lens so as to face the light receiving element on the stem. A sleeve capable of holding an optical fiber (ferrule) is joined to the cap member so as to face the condenser lens. Further, in the receiving optical module of this optical transceiver, the cap member has an opening for holding the lens, and the inner diameter of this opening is smaller than the diameter of the lens.

As described above, by applying the optical module of the present invention as the receiving optical module of the optical transceiver, it is possible to easily realize the compactness of the entire optical transceiver. Of course, in such an optical transmitter / receiver, the optical module of the present invention can be applied as a transmitting optical module.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an optical module and an optical transceiver according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an optical transceiver according to the present invention, and FIG. 2 is an exploded perspective view of the optical transceiver shown in FIG. Optical transceiver 1 shown in these drawings
Is an optical data link module called an SFF (Small Form Factor) type. This optical transceiver 1 is called an LC type 2
It has a receptacle 2 that can be coupled to the optical fiber connector and that receives the optical connector. The two-core LC type optical connector includes one ferrule with a diameter of 1.25 mm for the transmission connector and one for the reception connector.
Correspondingly, the receptacle 2 has a hole 2t for the transmission connector and a hole 2r for the reception connector, and the opening width of the receptacle 2 including the holes 2t, 2r is about 12 mm. It is said that.

As shown in FIGS. 1 and 2, the receptacle 2 is connected to the housing 3. The housing 3 includes a housing body 4 and a cover member 5.
A receiving optical module 20 and a transmitting optical module 20A, which are optical modules according to the present invention, are supported on the housing body 4 so as to be located behind the corresponding holes 2t, 2r. The housing body 4 has a partition wall 4a extending in the longitudinal direction thereof. The partition wall 4a partitions an area for accommodating the reception optical module 20 and an area for accommodating the transmission optical module 20A.

The receiving optical module 2 of the partition wall 4a
The 0-side wall surface is covered with a metal shield member 6. The cover member 5 has a substantially rectangular parallelepiped shape with an open bottom and an end on the side of the receptacle 2, and covers the housing body 4 from above. From the bottom edge of the cover member 5,
A plurality of stud pins 5a used when mounting (fixing) the optical transceiver 1 on a predetermined circuit board are extended.
The stud pin 5a also serves as a ground terminal for the shield member 6 provided on the housing body 4.

The receiving optical module 20 is capable of converting an optical signal from the optical fiber for transmission contained in the optical connector received by the receptacle 2 into an electric signal and outputting the electric signal. On the other hand, the transmission optical module 20A is
It is capable of converting an input electric signal into an optical signal and transmitting the optical signal to a receiving optical fiber included in an optical connector received by the receptacle 2. As shown in FIG. 2, the receiving optical module 20 is connected to the receiving circuit board 7, and the transmitting optical module 20A is connected to the transmitting circuit board 8. The receiving circuit board 7 includes a main amplifier that amplifies an electric signal from the receiving optical module 20,
A circuit for extracting a clock component from the signal, a data reproducing circuit for extracting the signal in synchronization with the clock component, and the like are mounted. Further, the transmitter circuit board 8 has an optical signal output automatic stabilizing circuit (APC: AutoPowerCon).
(troll) and the like are implemented.

A terminal pin group 9 is arranged on the housing body 4. The receiving circuit board 7 and the transmitting circuit board 8 are electrically connected to the circuit board on which the optical transceiver 1 is mounted via the terminal pin group 9. A stud pin 4b extends from the bottom of the housing body 4. The stud pin 4b is also used when mounting (fixing) the optical transceiver 1 on a predetermined circuit board, and also plays a role as a ground terminal of the shield member 6 provided in the housing body 4.

3 to 6 show an optical module provided in the optical transmitter / receiver 1 described above. Hereinafter, an optical module according to the present invention will be described with reference to these drawings, taking a receiving optical module as an example.

As shown in FIG. 3, the receiving optical module 20 is a so-called coaxial type optical module. The receiving optical module 20 includes a spherical condenser lens 21 and a photodiode (light receiving element, that is, photoelectric conversion element) 2
It includes an electronic circuit 23 including 2 and a package 28 that houses these components. In the receiving optical module 20, the optical signal from the optical fiber included in the optical connector is converted into an electric signal by the photodiode 22. The electric signal output from the photodiode 22 is processed by the electronic circuit 23 and then output to the outside. The electronic circuit 23 includes a preamplifier 24, in addition to the photodiode 22, as shown in FIGS.
Two capacitors (decoupling capacitor, Die
-Cap) 25 and 26.

The package 28 is composed of a stem 29, a cap member 30, and a sleeve 35. The above-mentioned photodiode 22, preamplifier 24,
The capacitors 25 and 26 are supported by the stem 29. A tubular cap member 30 is joined to the stem 29, and the photodiode 22 and the like are sealed by the cap member 30. The cap member 30 holds the condenser lens 21 so as to face the photodiode 22 on the stem 29. A sleeve 35 capable of holding a ferrule (optical fiber) of an optical connector is joined to the cap member 30 so as to face the condenser lens 21.

The configuration of the receiving optical module 20 and each component will be described in detail. First, the stem 29
Fe, which is a general constituent material of semiconductor packages
It is formed in a disk shape from (iron) or Fe whose surface is plated with Ni. The diameter of the stem is currently about 3.8 mm, which is considered to be the minimum value. It is considered that the diameter of the stem 29 can be further reduced by providing the preamplifier 24 of the electronic circuit 23 and the capacitors 25 and 26 outside the package 28. However, in the present invention,
The entire electronic circuit 23 (photodiode 22, preamplifier 24, capacitors 25 and 26) is housed inside the package 28 in consideration of the noise resistance characteristic of the output signal of the photodiode 22. The thickness of the stem 29 is
It is about 1 mm, and the component mounting surface is formed flat.

Further, as shown in FIGS. 3 and 4, the stem 29 has a total of five lead pins 40a to 40e.
Is fixed. The five lead pins 40a to 40e of the receiving optical module 20 are respectively GND (ground), VPD (light receiving element power supply), VCC (amplifier power supply), Out (signal output), / Out (inverted signal output).
It corresponds to. Each of the lead pins 40a to 40e is made of Fe.
Alternatively, the surface is formed of Fe with Ni plating. The diameter of each of the lead pins 40a-40e is about 0.3 mm.

The lead pin 40a for grounding is the stem 29
It is directly fixed to by welding. On the other hand, the remaining four lead pins 40b to 40e are pushed through holes having a diameter of about 0.6 mm formed in the stem 29. The low-melting-point glass is filled in the gaps between the lead pins 40b to 40e and the stem 29, and the two are fixed to each other. These four lead pins 40b-40e are
About 0.35 mm is projected from the component mounting surface of the stem.

As described above, the lead pin 40a for grounding is used.
Are directly fixed to the stem 29 by welding or the like. Further, the preamplifier 24 and the capacitors 25 and 26 are
It is directly mounted (fixed) on the component mounting surface of the stem 29. The separation surface of each of these components 24, 25, 26 (the surface in contact with the component mounting surface of the stem 29) is configured to function as an electrode. Therefore, the preamplifier 24 and the capacitors 25 and 26 fixed to the component mounting surface of the stem 29 are connected to the lead pin 40a, so that the preamplifier 24 and the capacitors 25 and 26 are grounded.

Of the two capacitors 25 and 26,
On the upper surface of one of the capacitors 25, the photodiode 2
Mounted (fixed) so that 2 is located in the center of stem 29
To be done. That is, a metal wiring pattern as an electrode is formed on the upper surface of the capacitor 25, and the cathode electrode C of the photodiode 22 is connected to this wiring pattern. The wiring pattern on the upper surface of the capacitor 25 is connected to the lead pin 40b for the light-receiving element power source via a bonding wire (for example, a gold wire of φ30 to 50 μm). As a result, the cathode electrode C of the photodiode 22 and the lead pin 40b for the light receiving element power supply are connected via the capacitor 25. The power supply signal smoothed by the capacitor 25 is applied to the photodiode 22.

On the other hand, the anode electrode A of the photodiode 22 is connected to the wiring pattern on the surface of the preamplifier 24 via a bonding wire. Preamplifier 24
Of the two output terminals included in the surface wiring pattern of the lead pins 40d and 40e via the bonding wires.
Respectively connected to. A metal wiring pattern is also formed on the surface of the capacitor 26. One end of the wiring pattern of the capacitor 26 is connected to the lead pin 40c via a bonding wire.
The other end of the wiring pattern 6 is connected to the wiring pattern on the surface of the preamplifier 24 via a bonding wire. As a result, the preamplifier 24 has a capacitor 26
Gives a smoothed power supply signal.

Under such a configuration, the optical signal from the optical connector (optical fiber) is transmitted to the photodiode 22.
The light-to-electricity is converted into a current signal and is sent to the preamplifier 24 as a current signal. As can be seen from FIG. 5, the preamplifier 24 is a so-called transimpedance amplifier TIA.
And is configured monolithically to include a transimpedance TI. The resistance value of the transimpedance TI is about several kΩ to 50 kΩ. Therefore, most of the current signal generated by the photodiode 22 flows into the transimpedance TI due to the very high input impedance of the preamplifier 24. Then, when a current flows into the transimpedance TI, a voltage is generated across the transimpedance TI. As a result, the current signal from the photodiode 22 is converted into a voltage signal. At the same time, the preamplifier 24 generates a complementary signal having a phase difference of 180 ° from the input current signal. As a result, the Out signal is sent from the lead pin 40d, and the / Out signal is sent from the lead pin 40e.

In this embodiment, the preamplifier 24
Has a rectangular planar shape with a side length of about 0.7 to 1.5 mm and a thickness of about 0.3 to 0.4 mm. As the preamplifier 24, a Si bipolar IC may be used when the optical signal frequency is about several hundred MHz, and when the optical signal frequency exceeds 1 GHz, when the GaAs device exceeds 10 GHz. , ICs made of SiGe other than GaAs devices
May be used.

Further, in this embodiment, as the capacitors 25 and 26, parallel plate capacitors having a capacitance of about 400 to 2500 pF are adopted. The capacitor 25 arranged between the lead pin 40b for the light receiving element power supply and the lead pin 40a for grounding has a rectangular planar shape, and is arranged between the lead pin 40c for amplifier power supply and the lead pin 40a for grounding. Capacitor 26
Has a square planar shape with a side length of about 0.5 mm. The thickness of each capacitor 25 and 26 is 0.
It is about 2 to 0.4 mm.

Further, in the present embodiment, as the photodiode 22, an InGaAs type surface receiving PIN-photodiode using InP as a substrate material is adopted. I
By changing the composition ratio of In and Ga, the nGaAs-based material has a main wavelength band of 1.3 in the optical communication.
It can be applied to both μm and 1.55 μm. The photodiode 22 has a side length of 0.3 to
It has a square planar shape of 0.5 mm and its thickness is
It is about 0.1 to 0.3 mm. The light-receiving surface that is sensitive to light has a circular shape with a diameter of 30 to 100 μm.

Now, the photodiode 2 on the stem 29
2 and the electronic circuit 23, the cap member 30 has a thickness of 0.
Fe-Ni- with Ni plating on the surface of about 15 mm
It is formed in a tubular shape from Co or Fe-Ni alloy. Here, the total height H of the cap member 30 is set to be lower (about 2.2 mm in this embodiment) than that of the conventional one (about 2.7 mm). Further, as shown in FIG. 6, the cap member 30 has an opening 30a at the top thereof for holding the condenser lens 21.
The opening 30a has a diameter D of the condenser lens 21.
The inner diameter D2 is smaller than 1. In the present embodiment, the condenser lens 21 is formed in a spherical shape having a diameter of about 1.5 mm, while the aperture 3
The inner diameter of 0a is set to about 1.12 mm, which is smaller than that.

Thus, if the inner diameter D2 of the opening 30a is smaller than the diameter D1 of the condenser lens 21, the opening 30a is formed.
Even if you secure a space for fixing the lens around the
It is possible to set the outer diameter of the portion of the cap member 30 located on the side of the opening 30a as small as possible within a range that does not hinder the fixation of the condenser lens 21. Therefore, as shown in FIGS. 3 and 6, the cap member 30 includes a cylindrical large-diameter portion 31 having a diameter φ1 located on the stem 29 side and a cylinder having a diameter φ2 located on the condensing lens 21 side. A small diameter portion 32.

The diameter φ2 of the small diameter portion 32 is set smaller than the diameter φ1 of the large diameter portion 31. In this embodiment,
The diameter φ2 of the small diameter portion 32 is about 0.5 mm after securing a ring-shaped area of 0.5 mm width around the opening 30a in consideration of fixing the spherical lens 21 having a diameter of about 1.5 mm on the opening 30a. The diameter is reduced to 2.2 mm. If the diameter of the condenser lens 21 is further reduced, the diameter of the small diameter portion 32 can be further reduced. On the other hand, the diameter φ1 of the large diameter portion 31 is set to about 3.5 mm so as to match the diameter of the stem 29. Further, the internal height H1 of the large-diameter portion 31 is set to approximately 0.7 mm so as to be necessary and sufficient to accommodate the electronic circuit 23 including the photodiode 22.

The cap member 30 thus constructed
After the condenser lens 21 is fixed, the condenser lens 2
1 is joined to the stem 29 so that the optical signal from the optical connector (optical fiber) is accurately focused on the light receiving surface of the photodiode 22 on the stem 29. As a result, the condenser lens 21 is offset toward the sleeve 35, as shown in FIG.
Held by. That is, the condenser lens 21 is fixed to the opening 30 a so as to be located between the cap member 30 and the sleeve 35.

In the optical module 20 according to the present invention, as shown in FIG. 3, the small diameter portion 32 of the cap member 30 and the sleeve 35 are mainly joined to each other by an ultraviolet curable resin or the like. The sleeve 35 is formed of resin or metal in a substantially cylindrical shape, and has a cylindrical connecting portion 36 and a cylindrical ferrule holding portion 37 having a diameter smaller than that of the connecting portion 36. The connecting portion 36 has a hollow portion 36a inside,
The small diameter portion 32 of the cap member 30 is inserted and fixed in the hollow portion 36a. In this embodiment, the cavity 3
The inner diameter of 6a is determined so that an adjustment allowance is secured when the optical fiber of the optical connector and the photodiode 22 are aligned on the XY plane (a plane perpendicular to the optical axis).

As described above, in this optical module 20, the cap member 30 has the small diameter portion 32 and the opening 30a.
The diameter of the side part is reduced. Therefore, in order to secure the strength of the sleeve 35 itself and the adhesive strength between the cap member 30 and the sleeve 35, even if the thickness of the connection portion 36 is secured to some extent, the outside of the connection portion 36 that determines the maximum outer diameter of the sleeve 35 is secured. It is possible to make the diameter at least as large as the outer diameter of the stem 29, or even smaller. In this embodiment, the thickness of the side wall of the connecting portion 36 is about 0.5 mm, and the outer diameter of the connecting portion 36 is about 3.4 mm, for example.

The ferrule holding portion 37 of the sleeve 35 is
It extends from the connection portion 36. Ferrule holder 37
Has a ferrule insertion hole 37a opened on the side opposite to the cavity 36a of the connecting portion 36. Ferrule holder 3
The size of 7 (ferrule insertion hole 37a) is determined based on the standard of the optical connector to be connected. That is,
In the present embodiment, the outer diameter of the ferrule holding portion 37 is set to about 2.8 mm and the total length thereof is set to about 4.5 mm so as to fit the LC type optical connector equipped with the ferrule having the outer diameter of 1.25 mm. To be done. The inner diameter of the ferrule insertion hole 37a is 1.25 mm + 2 μm. As a result, the optical axis can be aligned simply by inserting the ferrule of the optical connector into the ferrule insertion hole 37a.

As shown in FIG. 3, a conical concave portion 36b for accommodating the condenser lens 21 is formed inside the connecting portion 36 of the sleeve 35. The recess 36b communicates with the ferrule insertion hole 37a through the communication hole 36c formed in the connecting portion 36. The inner diameter of the communication hole 36c is approximately 0.4 mm, and the length thereof is approximately 1.0 mm. When the ferrule of the optical connector is inserted into the ferrule insertion hole 37a, the front end surface of the ferrule abuts against the end surface 36d of the connecting portion 36.

Next, a method of manufacturing the above-mentioned optical module 20 will be described. First, the lead pins 40a to 40e are fixed to the stem 29 at predetermined positions by the method described above. An electronic circuit 23 including the photodiode 22 and the like is mounted on the component mounting surface of the stem 29. In this case, a conductive adhesive is applied to the back surfaces (ground planes) of the preamplifier 24 and the capacitors 25 and 26, and they are placed at a predetermined position on the stem 29. Further, a conductive adhesive is applied to the back surface of the photodiode 22 and placed on the front surface of the capacitor 25 at a predetermined position. Then, in order to volatilize the solvent of the conductive adhesive, each part is heat-treated. Electronic circuit 23
After the above components are adhered onto the stem 29, the photodiode 22, the preamplifier 24, and the capacitors 25 and 26 are connected to the corresponding lead pins 40b to 40e by bonding wires.

Next, the cap member 30 is joined to the stem 29 by resistance welding.
Prior to joining to the stem 29, the condenser lens 21 is fixed in advance by using the jig 50 shown in FIG. 7. The jig 50 shown in FIG. 7 includes a main body 51 made of metal or the like, and a plurality (two) of V-shaped grooves 52 formed in the main body 51 so as to intersect (orthogonal) with each other. . The width d of each groove 52 and the value of the angle α are such that the diameter of the portion of the lens 21 protruding from the surface of the main body 51 when the spherical focusing lens 21 is placed at the intersection of the grooves 52 is a cap. The diameter is set to be slightly smaller than the diameter of the opening 30a of the member 30.

In this case, if the spherical condenser lens 21 is placed at the intersection of the grooves 52, the cap member 30 and the condenser lens 21 have the opening 30 as shown in FIG.
It is placed on the jig 50 so as to fit into a. This allows
The end surface of the cap member 30 (small diameter portion 32) contacts the surface of the main body 51, and the condenser lens 21 can be positioned easily and accurately with respect to the opening 30a of the cap member 30. Therefore, the mounting accuracy of the condenser lens 21 in the optical module 20 can be improved. Then, a ring-shaped pellet P made of low-melting glass or the like is placed inside the cap member 30 (small diameter portion 32) so as to be located around the condenser lens 21.

In this case, of course, the pellet P
For example, a lens having an outer diameter smaller than that of the condenser lens 21 can be used. In this embodiment, the pellet P
Has an inner diameter larger than the inner diameter D2 of the opening 30a by about 0.2 mm and an outer diameter smaller than the inner diameter of the small diameter portion 32. When the pellet P is placed at a predetermined position, a predetermined heat treatment is performed to melt the pellet P. This allows
The condenser lens 21 is fixed to the cap member 30.

On the other hand, at the end of the cap member 30 on the stem 29 side, as shown in FIG. 6, a projection 31a having a triangular cross section is formed over the entire circumference. When joining the cap member 30 to the stem 29, the projection 31
A large current is supplied to the contact portion between the two while a is abutted against the stem 29. As a result, the current density at the top of the protrusion 31a is increased, the protrusion 31a is locally melted, and the cap member 30 is welded to the stem 29. This welding operation is performed in an inert gas (nitrogen) atmosphere. In addition, in the work up to this point, individual alignment work is not performed,
Alignment depends only on the dimensional accuracy of each part.

When the cap member 30 is fixed to the stem 29, the sleeve 3 is attached to the small diameter portion 32 of the cap member 30.
Join 5 In this case, first, after applying a UV curable adhesive to the outer peripheral surface of the small diameter portion 32 of the cap member 30,
The small diameter portion 32 is inserted into the hollow portion 36a. Next, the ferrule of the optical connector is inserted into the ferrule insertion hole 37a of the sleeve 35 with the optical signal actually passed through the optical fiber. Further, an optical signal is emitted from the optical fiber, and the condenser lens 21 is brought into contact with the photodiode 22 to receive it. Then, the engagement state between the cap member 30 and the sleeve 35 is adjusted while monitoring the light receiving state of the photodiode 22. When the optimum position is determined by this adjustment work, each part is fixed in that state and UV irradiation is performed to cure the UV curable adhesive. Further, a resin for main fixing is injected between the cap member 30 and the sleeve 35, and heat-treated in an oven to be cured. Thereby, the optical module 20 is completed.

As described above, in the optical module 20 of the present invention, the opening 30a for holding the spherical condensing lens 21 of the cap member 30 has the condensing lens 2.
It is formed to have an inner diameter D2 smaller than the diameter D1 of 1. As described above, if the inner diameter D2 of the opening 30a is smaller than the diameter D1 of the condenser lens 21, even if a space for fixing the lens (arrangement space of the pellet P) is secured around the opening 30a, the cap member 30 has a space. Opening 30
It is possible to set the outer diameter φ2 of the portion located on the a side (small diameter portion 32) to be as small as possible within a range that does not hinder the fixation of the condenser lens 21. If the outer diameter φ2 of the cap member 30 on the side of the opening 30a is reduced in this way, the sleeve at the bonding portion is secured in order to secure the strength of the sleeve 35 itself and the bonding strength between the cap member 30 and the sleeve 35. Even if the wall thickness of 35 is secured to some extent (about 0.5 mm), the maximum outer diameter of the sleeve 35 can be reduced to at least about the same as the outer diameter of the stem 29, or even smaller (at least 4 mm or less). Becomes

Therefore, according to the present invention, the optical module 2
0 package 28 can be made compact, the mounting density of the optical modules 20 on the circuit board can be easily increased, and the entire optical transceiver 1 including such an optical module 20 can be made compact, that is, It is possible to easily improve the packaging density of the transceiver 1. Further, the condenser lens 21 held by the cap member 30 is arranged in an offset state on the sleeve 35 side. Therefore, if the total height H of the cap member 30 is appropriately determined, it is not necessary to review the entire optical system, and the condenser lens 21 can be easily fixed to the cap member 30.

Although detailed description is omitted, in the optical transceiver 1 according to the present invention, the transmitting optical module 20A including a light emitting element for converting an electric signal input to an electronic circuit into an optical signal is also used as a receiving optical module. Similar to 20, it has a cap member including a large diameter portion and a small diameter portion. As a result, the transmission optical module 20A is also made compact, so that the optical transceiver 1 according to the present invention can easily make the entire package compact.

FIG. 9 is a partial sectional view showing another embodiment according to the present invention. The same elements as those described in connection with the above-described embodiment are designated by the same reference numerals, and duplicate description will be omitted.

Optical receiving module 20B shown in FIG.
Then, the condenser lens 21 is fixed to the opening 30 a so as to be located between the cap member 30 and the stem 29. In this case, the total height of the cap member 30 is as shown in FIG.
Is larger than that of the example shown in. Specifically, the internal height H1 of the large-diameter portion 31 is maintained as it is, and the height of the small-diameter portion 32 is set to be larger than that of the example shown in FIGS. 3 and 6. Under such a configuration, the condenser lens 21 is offset toward the stem 29, and most of it is housed inside the cap member 30 (small diameter portion 32).

If such a structure is adopted, the contact area between the cap member 30 and the sleeve 35 becomes large, so that
The joint strength between the two can be improved. Also,
If the total height of the cap member 30 is properly determined, the stem 29
Since the relative position of the condenser lens 21 with respect to the (photodiode 22) and the sleeve (ferrule) can be maintained in the same manner as the receiving optical module 20 shown in FIG. 3, it is not necessary to review the entire optical system. Becomes

[0060]

As described above, according to the present invention, it is possible to realize an optical module and an optical transceiver which have a compact package and can increase the mounting density on a circuit board.

[Brief description of drawings]

FIG. 1 is a perspective view showing an optical transceiver according to the present invention.

FIG. 2 is an exploded perspective view of the optical transceiver shown in FIG.

3 is a partial cross-sectional view showing an optical module of the present invention included in the optical transceiver of FIG.

FIG. 4 is a perspective view showing a configuration around a stem included in the optical module of FIG.

5 is a circuit diagram showing a circuit configuration of the optical module of FIG.

6 is a cross-sectional view showing a cap member that constitutes the optical module of FIG.

FIG. 7 is a perspective view showing a jig used for fixing a lens to a cap member.

FIG. 8 is a partial cross-sectional view for explaining the procedure of fixing the lens to the cap member.

FIG. 9 is a partial cross-sectional view showing another embodiment of the optical module according to the present invention.

[Explanation of symbols]

1 Optical transceiver 2 receptacle 3 housing 4 housing body 5 Cover member 20,20B Receiving optical module 20A transmission optical module 21 Focusing lens 22 Photodiode 23 Electronic circuit 24 Preamplifier 25,26 capacitors 28 packages 29 stems 30 Cap member 31 Large diameter part 32 Small diameter part 35 sleeve 36 Connection 36a cavity 36e extension part 37 Ferrule holder 37a Ferrule insertion hole 40a, 40b, 40c, 40d, 40e Lead pin 50 jigs 51 body 52 groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Ito             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works F-term (reference) 2H037 AA01 BA03 BA12 CA14 DA03                       DA04 DA05 DA12 DA13                 5F088 AA01 BA15 BB01 EA07 JA03                       JA07 JA12 JA14 JA20

Claims (9)

[Claims] 1. An optical module having a spherical lens and an electronic circuit including a photoelectric conversion element, wherein the photoelectric conversion element converts one of an optical signal and an electric signal into the other, A stem that supports the electronic circuit that includes, a cylindrical cap member that is joined to the stem and that holds the lens so as to face the photoelectric conversion element, and a joint that is joined to the cap member and faces the lens. And a sleeve capable of holding an optical fiber so that the cap member has an opening for holding the lens, and the inner diameter of the opening is smaller than the diameter of the lens. Optical module to do. 2. The cap member, on the stem side,
While including a large diameter portion having a first outer diameter, on the opening side,
The optical module according to claim 1, comprising a small diameter portion having a second outer diameter smaller than the first outer diameter. 3. The optical module according to claim 1, wherein the lens is fixed to the opening so as to be located between the cap member and the sleeve. 4. The optical module according to claim 1, wherein the lens is fixed to the opening so as to be located between the cap member and the stem. 5. The optical module according to claim 1, wherein the maximum outer diameter of the sleeve is 4 mm or less. 6. The light according to claim 1, wherein the photoelectric conversion element is a light receiving element that converts an optical signal input via the optical fiber into an electrical signal. module. 7. The electronic circuit further includes a preamplifier that amplifies an electric signal from the light receiving element, and a capacitor that smoothes a power supply signal to the light receiving element and the preamplifier. The optical module according to claim 6. 8. The optical module according to claim 1, wherein the photoelectric conversion element is a light emitting element that converts an electric signal input to the electronic circuit into an optical signal. 9. An optical transceiver having a receiving optical module and a transmitting optical module, wherein an optical signal is transmitted and received using the receiving optical module and the transmitting optical module, wherein the receiving optical module The module has a spherical condensing lens and an electronic circuit including a light receiving element, is capable of converting an optical signal into an electric signal by the light receiving element, and a stem that supports the electronic circuit including the light receiving element. A cylindrical cap member that is joined to the stem and holds the condenser lens so as to face the light receiving element; and an optical member that is joined to the cap member and faces the condenser lens. A sleeve capable of holding a ferrule with a fiber, wherein the cap member has an opening for holding the lens, and the inner diameter of the opening is smaller than the diameter of the lens. Optical transceiver characterized that no.